In the long and distant past, when I owned a istDS, I also bought that grip. it works nicely as grip with shutter realease. BUT the build quality is below par. The first time I opened the door to gain access to the istDS's battery compartment, the whole grip fell apart. When I disassembled it, to reattach the springs etc. all the internal plastic threads broke lose and I had to use generous amounts of "liquid metall" (you this glue stuuf, which is a bit like play dough, but hardens ) to completely rebuild the grip. Otherwise the internal cord for the integrated cable realease always got jammed somewhere inside the grip.

All in all a part worth about 40 USD in my personal opinion, and only so, if you are willing to make a DIY project of it.